1. Field of the Invention
The present invention relates to an improved air circulation system for liquid-type electrophotographic printers and which is capable of saving energy for air circulation.
2. Description of the Related Art
As shown in FIG. 1, a liquid-type electrophotographic printer, for example, a color laser printer, includes a developer unit 20 for developing a latent electrostatic image formed onto a photoreceptor belt 10, a drying unit 40 for drying the developed image, and a transfer unit 30 for printing the image which has been developed and dried, on a paper. Such units are essential portions for a printing process, and are collectively called the engine of the printer. The engine is enclosed by a shield 50 in order to prevent foreign materials that are hazards to humans, from being discharged to the outside. The shield 50 has a discharge portion 51 connected to an air pump 80, and the air in the space enclosed by the shield 50 is discharged to the outside of the printer via the discharge portion 51. In FIG. 1, reference numeral 90 represents a filter for filtering out harmful fumes. In general, the harmful fumes in the space enclosed by the shield layer is generated by evaporation of carrier contained in a development solution by contact with the high-temperature photoreceptor belt 10, during the development, drying and transferring processes.
Meanwhile, the developer unit 20 includes a development roller 24 for developing a latent electrostatic image formed onto the photoreceptor belt 10 using a development solution containing a powdered toner and a solvent in a predetermined ratio, and a squeeze roller 21 and an air spray portion 22 which are for removing excessive development solution from the photoreceptor belt 10. The squeeze roller 21 presses the photoreceptor belt 10 to squeeze the solvent. The air spray portion 22 sprays air in order to prevent the squeezed solvent from flowing along the traveling direction of the photoreceptor belt 10, such that the solvent falls into the developer unit 20. In this case, a part of the air which is discharged by the air pump 80 is reused as a source of the air used by the air spray portion 22.
However, most harmful materials floating in the air that circulates in the space of the printer or is discharged therefrom, are generated by evaporation of the solvent contained in the development solution. Mostly, such evaporation of the solvent occurs at the photoreceptor belt 10. That is, the solvent is evaporated by the photoreceptor belt 10 that has been heated through the development, drying and transferring processes.
However, in the case of adopting the above structure, the shield 50 encloses all of the developer unit 20, the drying unit 40 and the transfer unit 30, in addition to the photoreceptor belt 10 that is the major origin of evaporated harmful solvent, thus the capacity of the air pump 80 for sucking air from such a large space enclosed by the shield 50 increases. Accordingly, energy consumption also increases by as much as the capacity of the air pump.